Accuracy of Pre-operative Imaging Predictors of Shamblin Grades in Carotid Body Tumors

Background and Purpose: Magnetic resonance imaging (MRI) is both sensitive and specific imaging modality in the diagnosis and surgical planning of carotid body tumors (CBTs). Radiological criteria to predict Shamblin grades has been described based on MRI, however, literature validating the same is sparse. The purpose of this study was to evaluate the accuracy of radiological criteria used to predict Shamblin grades in correlation with pre-operative grading. Materials and Methods: MRI images of 11 patients diagnosed to have CBTs during April 2014 to July 2016 at our institution were correlated with per-operative Shamblin grade. Radiologically, the tumors were classified into 3 types based on the arc of vascular contact with the internal carotid artery (ICA); contact ≤180° was categorized as Type 1, Type II tumors had more than 180° and <270°, and Type III tumors had a maximum circumference of contact of 270° or more. Results: Of the 11 patients, two patients were excluded from our study, one had bilateral carotid tumors on imaging and was operated elsewhere, and the other two, histology of one was vagal schwannoma, and the others were a nodal metastatic adenocarcinoma. Of the eight, six were Type II, one was Type 1, and one was Type III. Pre-operative prediction of Shamblin grades correlated accurately with per-operative Shamblin group in all the 8 operated tumors. Conclusions: MRI can accurately predict Shamblin group preoperatively based on the degree of circumferential contact of the CBT with the ICA on axial images.